Title

Author

Date of Award

2013

Document Type

Thesis

Degree Name

Master of Science

School

College of Arts and Sciences

Program

Biology MS

First Advisor

Gordon Atkins

Abstract

Glaucous-winged gulls (Larus glaucescens) breed along the Pacific Northwest coast where they perform highly stereotypical behavior patterns, including associated vocalizations. Early studies suggested the copulation call functions in maintaining pair bonds. Recent studies, however, challenge the idea that strengthening pair bonds is the only function of this call. I described the spectral and temporal features of the copulation call and investigated whether copulation behaviors varied over the course of the 2012 nesting season. During continuous observations from a blind in daylight hours, I documented the start and stop time for every copulation in a sample area of a nesting colony on Protection Island, Washington for three weeks during the copulation and egg-laying stage of the breeding season. I determined the average fundamental frequency, syllable duration, syllable interval, call duration, and number of harmonics of the copulation call for gulls in the sample area. An increase in mount duration was associated with an increase in day of year and a decrease in wind speed. An increase in mount interval was associated with an increase in time of day, barometric pressure, solar elevation, and a decrease in solar radiation and colony occupancy. The description of the temporal and spectral features for the copulation call established the foundation upon which future work on Glaucous-winged Gull copulation behavior can be built.